And if you think you can just buy a "penny turtle" think again because they don't exist.
"They sound cute and cuddly but they actually don't exist," NT Parks and Wildlife ranger Clare Pearce told the ABC.
Instead, Clare says people are probably buying hatchling freshwater turtles, which can grow quite large.
"They will outgrow most aquariums or tanks within a couple of years and either need a bigger tank or a pond — and they'll definitely need a pond by the time they're five or six years old," she said.
As well as their size, turtles have a long lifespan.
"Depending on the species, you could be looking at anywhere from 20 to 25 and 40 years old," Clare said.
"They're a bit like the long-term commitment of keeping a cockatoo as a pet."
What you need to know before getting a turtle as a pet
According to the RSPCA website, keeping native freshwater turtles as pets is subject to permit or licensing restrictions, depending on the state or territory you live in.
If you have chosen a turtle as a pet it may need to be kept indoors away from predators. The World Of Animal Welfare website says all but the largest turtles can be kept in an aquarium approximately 1 metre long, with a water filter and a heater.
Additionally, water quality must be strictly maintained and appropriate lighting installed in the tank.
For more information on how to look after a turtle, visit the website.